In our parlance, a moon=a month. That's in fact what the word 'month' means. However, it might also mean a week, as in the span of time between moon days ('Monday'). Or it might even mean a day, being the time between each rising of the moon.

30 moons is about 819 days. Correct me if I'm wrong, but I think it would be in the cycle of days and years. So, the portal would have probably been closed for 819 days if Twilight did not get the crown back.

30 moons is about 819 days. Correct me if I'm wrong, but I think it would be in the cycle of days and years. So, the portal would have probably been closed for 819 days if Twilight did not get the crown back.

Plus I think 819 days/2.5 years is a bit more dramatic than just 30 days or 30 weeks.

"Twilight, if you dont get the crown, we will not see you for 3 years"

vs.

"Twilight, if you dont get the crown, your 30-day-trial of Earth-Portal will expire, lol sux bro"

Our lunar cycle is 28 days, but for all we know the Equestrian lunar cycle might be different. So technically, we don't really know how often that portal opens. But it's probably the same amount of time or the writers would have explained the difference.

2.5 years is a long time to be trapped in a place with no home or means of income. Considering she slept in the library, never bathed, and wore the same clothes, she would likely become that creepy uban legend of the hermit girl who lives in the school library and steals you socks, or something.

I don't know about anyone else, but to me, the timing in this film was very confusing. According to Celestia, the portal would be closed and wouldn't be opened again for thirty moons. So, how long is thirty moons? Thirty nights? Thirty weeks? I think this was explained in "Apple Family Reunion," but I could be wrong. Also, it seems that the hours in a day are the same as ours, that is twenty-four hours. Additionally, when Twilight does get to the human world, we learn that Sunset Shimmer has won the crown for the past three times in a row. Again, this is where the timing gets confusing. Exactly how much time has passed since Sunset Shimmer went through the mirror and when Twilight did the same? I don't recall this ever being explained in the film. I understand that this is a kids' film and they can't take the time to explain everything. they do have a time limit and kids generally do not have a long attention span. But that was just one thing that really hindered me from enjoying this film because I was trying to figure out the timing of events throughout the film.

When people use "moons" as a unit of time, they refer to the time between one full moon and the next one. Thus a single moon is 28 days. Thirty moons would be 840 days, which is about 2.3 years.

Admittedly it hasn't been used very accurately in the show; apparently the Apple Family Reunion is held once every 100 moons, however according to Applejack in Season 1 she had family members round for an Apple Family Reunion; so the next one would be seven and a half years later. Which is completely off the timeline we can observe for the series, the CMC would be grown up come S3E8

Another one of those references for the old timers that know of ol' western movies and such.

Or history buffs...

But yeah flipturn nailed it.

Another way to look at it though is roughly each month has 1 true full moon. So 30 months give or take

Admittedly it hasn't been used very accurately in the show; apparently the Apple Family Reunion is held once every 100 moons, however according to Applejack in Season 1 she had family members round for an Apple Family Reunion; so the next one would be seven and a half years later. Which is completely off the timeline we can observe for the series, the CMC would be grown up come S3E8

were they in town for a reunion? I thought it was for the party preparations and to help out..

30 moons refers to the time it takes for the moon to go through one lunar phase, or about 28 days per moon. As Flipturn above mentioned, it is a little over 2 years.

Yes, you are right in saying that Sunset won the crown three times in the past, but not the same one. When Twilight's crown was brought to the human world, it must have gotten switched with the "real" one, either because it looks like the one they were going to use or because it just looks like a nice enough crown to give away.

30 moons is usually about 30 lunar cycles. However, there is some dispute as to how long 30 moons is in Equestria. I've heard some form of date in Equestria, such as Tuesday or the 21st of so and so. Granny Smith mentions that the Apple Family reunion is every 100 moons, and the reunion before that was mentioned by Applejack to take place just before the Summer Sun Celebration. Some people think Granny Smith's 100 moons is her exaggeration of 100 days or a year. I think 30 moons, in Equestria, is 30 days. A month would seem about appropriate.